Recently, computerization of vehicles has been progressing, various equipments, driving systems, auxiliary systems for the same, etc. of the vehicle are equipped with a number of electronic equipments, and these electronic equipments are controlled. Further, in a control apparatus for controlling such an on-vehicle electronic equipment, in order to realize a safe operation of the vehicle and improve the convenience and comfortability of drivers, a high safety and a high reliability are required.
Therefore, in the control apparatus of the on-vehicle electronic equipment described above, in order to ensure the high safety and the high reliability, abnormality monitoring of a control program for controlling the electronic equipment is performed. Conventionally, in the control apparatus of the on-vehicle electronic equipment, a method that performs abnormality monitoring (abnormality detecting) by using a watchdog timer (WDT) is commonly known as a method for monitoring (detecting) abnormality of the control program.
In the conventional control program abnormality monitoring using the WDT, in the case that no abnormality occurs in the control program, the WDT is constantly cleared by a clear command within a prescribed time (before the time of the WDT is up), and counting of the WDT is restarted. On the other hand, in the case that an abnormality occurs in the control program, since the clear command is not executed, the time of the WDT is up, as a result, reset is executed, and it is possible for an abnormal execution state of the control program not to continue over a prescribed time.
For example, in the case that the above electronic equipment is an electric power steering apparatus, as described in Patent Document 1 (Japanese Published Unexamined Patent Application No. 2009-113618 A), a technique that accurately detects the abnormal execution state of the control program being undetectable by means of the WDT described above and by measuring a termination time of each task and performing detection of the abnormal execution state of the control program based on the measured termination time of each task by means of a control section, is disclosed.
Further, in Patent Document 2 (Japanese Published Unexamined Patent Application No. 2006-90356 A), a technique that suppresses the occurrence of faults such as task missing and so on by detecting a task with a high processing load in a control apparatus for vehicle control and replacing with processing contents with a lower processing load based on a predetermined task congestion criterion, is disclosed.